A fractional CTO in the UK typically costs £1,000 to £1,600 a day in published figures, with some sources quoting up to £2,500, usually bought as a monthly retainer for one or two days a week. An interim CTO, working close to full-time for a set period, runs to around £24,000 a month. A permanent CTO on a £150,000 salary costs about £173,000 a year once employer National Insurance and the minimum pension are added, before recruitment fees, equipment or equity.
If you’re still deciding which of those roles you need, start with fractional CTO, interim CTO or lead developer. This piece is about the money: what the market publishes, how it’s charged, what the permanent alternative really costs, and how to budget so you pay for decisions rather than hours.
What the market publishes
There’s no official survey of CTO day rates. There are directories and practitioners publishing figures, which are useful if you read them for what they are.
| Fractional Quest, citing Red Eagle Tech, September 2026 | £1,000 a day low, £1,200 to £1,400 typical, £1,600 high |
| Fractional Quest, citing Connectd | £900 to £1,600 a day |
| Martin Sandhu, July 2026 | Roughly £1,000 to £2,500 a day |
| Fractional Quest, citing Red Eagle Tech | £150 to £350 an hour for light-touch advice |
| Fractional Quest | London £1,200 to £1,600 a day; Manchester, Leeds and other regions £800 to £1,100 |
Why the figures disagree
Each source is describing a different slice of the market. A directory averages across everyone listed on it; a practitioner describes what experienced people serving funded companies charge. The overlap, roughly £1,000 to £1,600 a day, is the useful part. The tails depend on seniority, sector and how much the business has riding on the decisions.
London and everywhere else
Fractional Quest puts London specialists at £1,200 to £1,600 a day against £800 to £1,100 in Manchester, Leeds and other regions, and notes that remote-first work narrows the gap. For most ecommerce businesses, where the CTO works mostly remotely, the region matters less than the experience.
Hourly advice
The same source lists £150 to £350 an hour for light-touch advisory work. That suits a founder who wants a sounding board before a decision, not someone to own the technology.
How the money is structured
The day rate is only half the price. How the work is bought decides how much of it you use, and what you get for it.
A monthly retainer
Fractional Quest describes the retainer as the dominant UK model for ongoing leadership, at £3,000 to £7,000 a month for one to two days a week in Red Eagle Tech’s figures. Martin Sandhu works one day a week at £1,500 a day out to £6,000 to £7,500 a month, or £72,000 to £90,000 a year. A retainer buys continuity: the same person, the same context, every week.
A day rate
Day rates suit work with a shape: an architecture review, technical due diligence before an investment or acquisition, or a platform decision. You buy a defined number of days for a defined output, and the engagement ends when it’s delivered.
An interim engagement
An interim CTO covers a gap full-time or close to it. Sandhu’s example is four days a week at £1,500 a day: roughly £24,000 a month, or £288,000 annualised. It’s the most expensive way to buy the role by the month, and the right one for a known window, such as a departure, a migration or an acquisition.
Priced by outcome
The alternative to buying time is buying a result: the platform decision made and documented, the team restructured, the migration delivered. It’s how I price CTO work, because it puts the attention on what the business gets rather than how many days it took.
Against a permanent hire
The usual comparison is a fractional CTO against a full-time one. It’s only fair if the permanent cost includes everything the salary doesn’t.
| Salary | Example, within Sandhu’s £140,000 to £180,000 Series A/B range | £150,000 |
| Employer National Insurance | 15% above the £5,000 secondary threshold | £21,750 |
| Pension, legal minimum | 3% of qualifying earnings, £6,240 to £50,270 | £1,321 |
| Total before other costs | Before recruitment fees, equipment, benefits and equity | About £173,070 |
What the example leaves out
GOV.UK’s employer rates set employer National Insurance at 15% above £5,000 a year, and the workplace pension rules set a 3% employer minimum on qualifying earnings. Most senior hires get more than the minimum pension, and recruitment fees, equipment and equity sit on top. Fractional Quest’s loaded figure for a full-time CTO in year one, including those, is £192,500 to £255,000.
What the comparison usually misses
A fractional CTO costs a fraction of a permanent one because you get a fraction of their time. The fair comparison is which one gets the decisions you need made, at the pace you need them, for the least money.
When permanent wins
Once a business needs daily technical leadership, a growing team to manage and someone accountable full-time, the permanent hire is better value, and a good fractional CTO will tell you when you’ve reached that point.
How IR35 changes the sum
Most fractional and interim CTOs work through their own company, so the off-payroll rules can change what an engagement costs.
Who decides
HMRC’s guidance says that for small clients outside the public sector the worker’s own company decides whether the rules apply; for medium and large clients, the client decides and issues a status determination statement. The roles article sets out the April 2025 thresholds for what counts as small.
What an inside-IR35 engagement costs
If the rules apply, tax and National Insurance are deducted through payroll, and the fee-payer also pays employer National Insurance on the fee. That makes an inside engagement noticeably more expensive for the same day rate, and some contractors price differently as a result. Settle the status before comparing quotes.
Why the role matters
A fractional CTO on outcomes, working for several businesses, looks very different from an interim CTO managing your staff full-time. The closer the engagement is to a job, the more likely the rules apply.
◆ Questions about CTO costs
Often, yes. A contractor’s company must register for VAT once its taxable turnover goes over £90,000 in 12 months, which most full-time contractors pass, and then charges VAT on its invoices. A VAT-registered business can usually reclaim it; one that isn’t pays it as a cost. Ask whether a quoted rate includes VAT.
The published retainers are built around one or two days a week, which suits most growing stores with a technical decision or two to make each quarter. If the work fills more than that every week, you’re drifting towards an interim or a permanent hire.
Yes, and it’s the sensible way in. A few days on a defined question, such as a platform decision or an audit of the current setup, shows whether the person is right before any retainer starts.
Seniority, sector and what’s at stake. Someone who has taken a business through a funding round, an acquisition or a replatform charges for having done it before. The useful test is whether their past decisions match the ones you need made.
How to budget for it
◆ Budgeting for technical leadership
Do
- Start from the decisions you need made this year
- Cap the days, and review the cap every quarter
- Agree what the engagement delivers, and when it ends
- Settle IR35 status before comparing quotes
- Compare the total cost of the outcome, not the day rate
Don’t
- Buy days without a defined output
- Compare a fractional day rate with a salary divided by 220
- Retain an interim for a part-time, ongoing need
- Hire a permanent CTO for a one-off decision
- Assume the rules on employment status are someone else’s problem
How I price CTO work
I don’t have a day rate or a rate card. Fractional and interim CTO work is scoped around what the business needs to decide or deliver, priced on what that’s worth, and agreed in writing with a deposit before it starts. The fractional and interim CTO page explains how engagements work.
A first conversation
If you’re not sure whether you need a CTO at all, or which kind, that’s a thirty-minute question. Book a free call.
◆ Glossary
- Fractional CTO
- A senior technology leader working part-time, usually one or two days a week, for an ongoing period.
- Interim CTO
- A technology leader covering the role full-time or close to it for a set period, such as a gap between permanent hires.
- Retainer
- A fixed monthly fee for an agreed amount of time or scope, rather than billing day by day.
- Employer National Insurance
- The National Insurance an employer pays on employees’ earnings above the secondary threshold: 15% above £5,000 a year in 2026 to 2027.
- IR35
- The off-payroll working rules that decide whether a contractor working through their own company should be taxed like an employee.
- Status determination statement
- The document a medium or large client gives a contractor saying whether the off-payroll rules apply, and why.
◆ Sources
